Technical Bronze Distributor Gear

Just pulled the distributor out of my SBC that has a decent lift solid roller in it and the bronze distributor gear is pretty much toast. A buddy of mine said he decided to just run a steel gear after his SBC with a similar cam did the same. Is this a bad idea? Guessing the bronze is for a reason and it is better to wipe out the distributor gear than the gear on the cam…. Anyway, I have never run a bronze gear before so not sure how long they should last. Guessing this one has almost no miles to be honest…maybe 2-4k or so. It is just a street car but does get driven pretty hard at times. I need to go find the cam card and see what it says.

 

With an aftermarket billet roller cam, with a steel gear on the cam, the stock distributor gear is not compatible. It will eat up the gear on the camshaft. You just need to replace the bronze gear from time to time, or you can buy a melonized steel gear that will last longer and won't eat the gear on the cam. I'm not familiar enough with the oil gallery locations on your Chevy engine, but on my early Hemi, there is an oil gallery plug adjacent to the the cam gear. I drill a .030 hole in it so that there is a constant stream of oil spraying on the intersection of the cam gear and the distributor gear. It really helps the life of the bronze gears.

 

You need to see what the cam actually is . I'm sure it's a billet cam being a solid roller but some have an iron gear fused on them. I normally run a bronze gear on a billet cam but recently used a composite gear on a street BBC I built. We will see how that goes ... It wasn't cheap .

 

Thanks guys!

Found the cam card, but I may have to do some digging on what it actually is.

 

Need to run the correct gear .

 

https://www.summitracing.com/parts/cca-412m

 

Thanks again guys. I’m digging into this more since I didn’t put this motor together. I think I will call my connection at Comp tomorrow and see what he says I should run since he can pull up the specific cam by part number and SN since it is a custom grind. Not sure this is a billet cam at least from what I have found so far.

 

I bought a melonized gear for my roller. From my understanding the bronze gears do wear out and need to be changed periodically. Comp also recommends a composite gear.

Also, it is my understanding that all roller cams are billet steel.

I got my gear from Summit. It was not cheap.

https://www.summitracing.com/parts/sum-850466-m

 

While you have the gear off, take the time to also modify the housing with an oil spray groove cut across the lower oil band on the housing.
You can use a small file to cut a shallow groove aimed near the point of mesh between the cam and distributor gear, aligned to match the position your distributor will sit when installed in your engine.
All you need is about .010" wide and .005" deep.....a small triangle file works great for this.
If you are using the o-rings on your MSD housing, leave the bottom one off, even if you don't do the groove mod but especially if you do.

You want to keep that gear oiled to help it live.
It sometimes takes the bronze gear a bit of time to polish the steel cam gear up nicely, then the replacement gear lives a much longer life.

 

Bronze gears are great for race engines that you are constantly tearing down where you can keep an eye on them. They’ll work in street engines, but with extreme short lives compared to steel or cast gears. I’m running a steel gear in my 5.0 Ford, should not have to worry about it for a long time.

 

I'd stick with bronze.

 

I have not run a roller on the street. I had one in the race car, and have worked on other's cars with them. This is all tales from the garage, so take it as less backed up with science than what a cam maker will tell you.
Race cars run a much bigger portion of their lives at high RPM with higher oil pressures and spray. Street cars tend to run a lot at lower RPM and for longer periods of time. This is one factor.
Also as mentioned, nobody runs a race engine over 10 years and 100K miles without inspection or rebuild.
Those times when a gear has been chewed up, the bearings and rings followed soon after, even with good filters.

 

The bronze particulate has to go somewhere so change filters on the early side. Crane cams had a 'special' gear that I used a couple times on roller cammed Hemis and never had any issues or complaints. Don't know if it is the same/similar as the Comp material. Best ask them.

 

I asked Comp Cams and the recommendation was for either bronze, melanized, or composite with main recommendation being melanized. I plan to either run one of those or another bronze one.

 

Thanks for all the input everyone. I have definitely learned some things here.

 

Could you use a stock GM gear that was used with a stock hydraulic roller camshaft?

 

I ran mechanical roller cams in my race engines. For some reason I changed the magneto to one with a stock cast gear, I don't remember why. The stock gear wore out in maybe 3 or 4 races. I went back to a bronze gear and never had a problem. In fact I ran the one mag for about 10 years and the gear still looked like new. However, these were race engines and sprint car races aren't that long, not a lot of miles.

 

I suppose you could, but I had the distributor out of a late model roller 350 recently and I had to replace the gear, it was trashed. So they wear out too.

 

Your right they do the same thing, they get razor sharp.

 

Huh. A steel gear / steel hydraulic roller camshaft last forever in a stock setup.

 

Factory hydraulic roller cams aren't typically steel billet cores. I had to look it up because I couldn't remember..Austempered Iron is what's normally used.

 

Only thing I can add…I replaced the distributor in my daughter’s car (GM v8 hydraulic roller cam) at about 160k. Was cheaper and easier to replace than get parts, time to clean it up, etc.
there was no distributor gear wear, etc.

Kept it around for an oil priming tool, as mine never came back to me.

That said, I like the idea of the composite gear. 80 bucks seems like insurance. If bronze gears wear, seems that they run through the oiling path before the particulates get filtered.
I’d error on the side of caution.

 

Does Comp sell gears ? Guessing gears are not created equal.

 

Yes, and I was planning to buy one from the guy I know there…until he said they were out of stock (at least on the melanized one for an MSD).

 

You know, I suppose that if the oil pump was not driven by the same gear, that it would probably last forever, seeing as how a distributor has essentially no load. So maybe the answer is an external wet sump pump driven off the nose of the cam or by an external drive belt system. Would allow for a better design of the windage tray as well.

Of course small block Chevy engines have gone hundreds of thousands of miles using the stock cam, distributer gear and oil pump system on somewhere in the neighborhood of 100,000,000 engines. Maybe those cams that have a standard drive gear and can use the standard distributor gear deserve a closer look. And don't forget, maybe we shouldn't jack up the volume and pressure from the pump. Just some random thoughts...

 

2 things, different metal, as mentioned, and a ton more spring pressure on most solid rollers compared to a stocker hyd. As anyone who has spun an assembled motor over knows, they like to jump forward and back, and it's those impulses that go from a nice smooth sweep of the gear to a hopscotch on the face.

 

Good catch. I have seen evidence of the oscillation on just about every EarlyHemi that I have worked on. I expect that all engines experience some.

 

Comp is always out of stock on everything. Just went through this. I got the part numbers and was able to find what I needed through Summit and eBay.

Jeff if you have measurements of the gear you need you can likely find one at Summit. They have shaft measurements in the info. And, free shipping over $100. So depending on what gear you get you should make that.

 

Thanks Dan. I also need a few other parts for this MSD distributor and seems Speedway may be the best bet. I have them in my cart, just haven’t fully committed yet.

 

I have a Comp Cams custom grind solid roller in my BBC, with MSD pro billet dist.
The cam is a billet core from the mid 2000s, and was told by Comp Cams, must use bronze dist gear or composite.

Used a bronze gear at first and was short lived, started to wear.
Changed to the composite gear and its been in the engine for more than 10,000 miles on it, and no wear.

The only thing I did different was go from 20/50 oil to 10/30 to take some load off the gear, due to being worried about the load on the gear turning the oil pump.
Don't know if that was really necessary or not, don't even think about it anymore.

From what I understand, newer billet cams do not need the bronze or composite gear due to being manufactured differently.

So I guess figuring out how old the cam is, is the main factor of what type of gear to use.

A melonized gear will tear up an older billet cam, from what I understand.

Bill